Asphalt emulsion based surface treatments such as asphalt slurry and microsurfacing are used to maintain asphalt pavements. The application of such surface treatments extends the life of existing pavements and repairs pavement surface problems such as raveling (loss of aggregate), weathering, wheel path rutting, and loss of roughness or slick wheel paths. The slurry can be mixed by a mobile slurry machine and applied to the pavement surface in a continuous or batch process. One such mobile paving system is disclosed in U.S. Pat. No. 5,590,976, entitled "Mobile Paving System Using an Aggregate Moisture Sensor and Method of Operation."
A mobile paving system can deposit slurry onto a surface through a box type screed pulled behind the slurry machine. The box type screed can be called a "spreader box." The ability of the mobile paving system to satisfactorily apply the slurry to the surface can depend upon the ability of the system to evenly distribute the slurry across the full width of the spreader box. Mobile paving systems can use auger flighting or paddles mounted on rotating shafts to distribute the slurry across the full width of the spreader box.
The spreader box width determines the width of the surface that can be treated. Current systems can allow operators to change the spreader box width by physically adding or removing sections of the spreader box, accompanying auger flights or paddles, and strike-off devices. A disadvantage associated with such systems is that the process to change sections is labor intensive and may take hours to accomplish when the box is covered with hardened slurry material. Because of the difficulty in changing the sections of the spreader box, operators of the mobile paving systems often do not adjust the spreader box. Most roadway surfaces require multiple passes of the spreader box to cover the entire roadway surface. This, in turn, may create overlap of the applied surfacing material as multiple passes of the mobile slurry machine pass over the same areas. Such overlap wastes slurry material and creates an uneven surface.